wip: don't lock command mutex for each mass/spring in FillGraph()

include/config.hpp

@@ -30,7 +30,7 @@ constexpr float ROT_SPEED = 1.0;
 constexpr float CAMERA_SMOOTH_SPEED = 15.0;
 
 // Physics Engine
-constexpr float SIM_SPEED = 4.0;          // How large each update should be
+constexpr float SIM_SPEED = 0.2;          // How large each update should be
 constexpr float TIMESTEP = 1.0 / 90;      // Do 90 physics updates per second
 constexpr float MASS = 1.0;               // Mass spring system
 constexpr float SPRING_CONSTANT = 5.0;    // Mass spring system

include/physics.hpp

@@ -83,7 +83,7 @@ public:
   std::unordered_map<std::pair<State, State>, int> state_springs;
 
 public:
-  MassSpringSystem() {
+  MassSpringSystem() : threads(std::thread::hardware_concurrency() - 1) {
 #ifndef BARNES_HUT
     last_build = REPULSION_GRID_REFRESH;
     std::cout << "Using uniform grid repulsion force calculation." << std::endl;
@@ -188,6 +188,10 @@ public:
   auto AddSpringCmd(const State &a, const State &b) -> void;
 
   auto ClearCmd() -> void;
+
+  auto AddMassSpringsCmd(const std::unordered_set<State> &masses,
+                         const std::vector<std::pair<State, State>> &springs)
+      -> void;
 };
 
 // https://en.cppreference.com/w/cpp/utility/variant/visit

src/main.cpp

@@ -39,7 +39,7 @@ auto main(int argc, char *argv[]) -> int {
   OrbitCamera3D camera;
   Renderer renderer(camera);
   ThreadedPhysics physics;
-  StateManager state(physics);
+  StateManager state(physics); // TODO: What is this warning?
   InputHandler input(state, renderer);
 
   std::vector<Mass> masses;                    // Read from physics
@@ -74,7 +74,7 @@ auto main(int argc, char *argv[]) -> int {
     */
 
     // Read positions from physics thread
-    // TODO: We're reading a HUGE amount of SHIT, because the state
+    // TODO: We're copying a HUGE amount of SHIT, because the state
     //       representations (std::string, ~100 Bytes) are copied ~3 times per
     //       spring: state_masses<State, int> and state_springs<<State, State>,
     //       int>

src/physics.cpp

@@ -366,11 +366,18 @@ auto ThreadedPhysics::PhysicsThread(ThreadedPhysics::PhysicsState &state)
     }
 
     // Physics update
+    // TODO: I need this thread to run at a constant rate
     mass_springs.ClearForces();
     mass_springs.CalculateSpringForces();
     mass_springs.CalculateRepulsionForces();
     mass_springs.VerletUpdate(TIMESTEP * SIM_SPEED);
 
+    // TODO: Notify the main thread of update
+    // TODO: Just wait here until the main thread has fetched the data?
+    //       Then only the copying would be sequential, while the main thread
+    //       renders this thread can already calculate the physics...
+    // TODO: Would std::swap help in any way?
+
     // Publish the positions for the renderer (copy)
     {
       std::lock_guard<LockableBase(std::mutex)> lock(state.pos_mtx);
@@ -402,3 +409,17 @@ auto ThreadedPhysics::ClearCmd() -> void {
     state.pending_commands.push(ClearGraph{});
   }
 }
+
+auto ThreadedPhysics::AddMassSpringsCmd(
+    const std::unordered_set<State> &masses,
+    const std::vector<std::pair<State, State>> &springs) -> void {
+  {
+    std::lock_guard<LockableBase(std::mutex)> lock(state.command_mtx);
+    for (const auto &_state : masses) {
+      state.pending_commands.push(AddMass{_state});
+    }
+    for (const auto &[from, to] : springs) {
+      state.pending_commands.push(AddSpring{from, to});
+    }
+  }
+}

src/state.cpp

@@ -37,12 +37,12 @@ auto StateManager::FillGraph() -> void {
 
   std::pair<std::unordered_set<State>, std::vector<std::pair<State, State>>>
       closure = current_state.Closure();
-  for (const auto &state : closure.first) {
-    physics.AddMassCmd(state);
-  }
-  for (const auto &[from, to] : closure.second) {
-    physics.AddSpringCmd(from, to);
-  }
+
+  physics.AddMassSpringsCmd(closure.first, closure.second);
+
+  // TODO: We have only dispatched the commands, the states won't be downloaded
+  //       when calling this... Make FindWinningStates() another command?
+  //       Or recalculate whenever masses.size() changes?
   FindWinningStates();
 }